Talat mashakel fee hayatna...Since wa For wa Ago

It's really not such a big moshkila, bas bardu....el nas betitlakhbat fehom:

For + a period of time: (general times)
1. I've been sitting here for 2 hours.
2. I'm going to travel for 6 months.
3. I've known her for a long time.

Since + the start of a period: (specific times)
1. I've been sitting here since 3:00
2. I've been traveling since June.
3. I haven't seen you since the feast.

For: two hours, 20 minutes, five days, six months, a week, 50 years, a long time, ages (masalan y3nee...of course all these can be subsitued, 20 minutes could be 25 minutes) (for is used for general times)

Since: 8:00, Monday, May 20, March, 2002, breakfast, New Years, I was a child (since is used for specific times)

Ago is usually used at the end of a sentence (or in the middle for a question):

- I lived in the States ten years ago. (mish I've been living in the States ten years ago).
- Where's Sally?I don't know. She was just standing here five minutes ago.
- How long ago did you begin this blog? (min imta)
I began this blog about one month ago.

Look at the difference in these sentences:
I broke my leg 8 months ago.(itkasarit min taman toshor)
I broke my leg for 8 months. (itkasarit le modit taman toshor. ( 8 months?? Leh? regl feel!)
I broke my leg since 8 months.(oulna since ma tinfa3sh ma3 general times)

mish 3arfah leh mo3zam el nas beyista3milu since ma3 ago:I went to the doctor since one week ago. (leh???) wa malha:I went to the doctor one week ago.

Easy exercise link:
http://http://a4esl.org/q/h/9807/km-sincefor.html

More difficult link:
http://http://cla.univ-fcomte.fr/english/grammar/tenses_time_words/05_michele/05_forago.htm